1. Field of the Invention
The invention relates to automotive fuel cell water management systems and methods of operating the same.
2. Discussion
An electrolyte fuel cell generates electricity by electrochemically reacting a fuel gas such as hydrogen and an oxidizer gas such as oxygen.
Some electrolyte fuel cells include a membrane comprising an electrolyte film and a catalytic layer formed on opposing surfaces of the electrolyte film. A gas-permeable and electrically conductive electrode layer is provided on an outer surface of each catalytic layer. An electrically conductive bipolar plate is provided on an outer surface of each of the electrode layers. The bipolar plates mechanically clamp the electrode layers and electrolyte film together.
A flow field or channel is formed on a surface of each bipolar plate facing the respective electrode layers. The flow fields direct gases to the electrode layers. The fuel gas is directed to one of the electrode layers. The oxidizer gas is directed to the other of the electrode layers.
During operation, hydrogen gas is taken in the electrode layer on a hydrogen gas supply side, e.g., anode, while passing along the surface of the electrode layer. The hydrogen gas diffuses and passes through the electrode layer to the anodic side catalytic layer. When the hydrogen gas inside the catalytic layer reaches a certain region, an electrochemical reaction takes place between the hydrogen gas and the electrolyte. The hydrogen gas is ionized by the reaction. The hydrogen ions are taken into the electrolyte film.
Oxygen gas is taken in the electrode layer on an oxygen gas supply side, e.g., cathode, while passing along the surface of the electrode layer. The oxygen gas diffuses and passes through the electrode layer to the cathodic side catalytic layer. The oxygen gas reacts with the hydrogen ions drifting from the anode through the electrolyte film producing water. During this reaction, electrons migrate from the anode to the cathode through an external load connected to the fuel cell anode and cathode thus generating electric power.